import java.util.Scanner;
 
class FrogJump {
 
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
 
        // Read number of stones and maximum jump length
        int n = sc.nextInt();
        int k = sc.nextInt();
 
        int[] heights = new int[n];
 
        for (int i = 0; i < n; i++) {
            heights[i] = sc.nextInt();
        }
 
        int[] dp = new int[n];
 
        dp[0] = 0;
 
        for (int i = 1; i < n; i++) {
            dp[i] = Integer.MAX_VALUE;
            // Math.max(1,i-k) will give us the jump the frog starts from
            // i=2 means 3 elems and we curr on 3rd elem we will see all k elem before i.
            // dp[i] = minimum cost to REACH Stone i, not the cost of standing on Stone i.
            for (int j = Math.max(0, i - k); j < i; j++) {
                dp[i] = Math.min(dp[i],
                        dp[j] + Math.abs(heights[i] - heights[j]));
            }
        }
 
        System.out.println(dp[n - 1]);
        sc.close(); // Close the scanner
    }
}
 

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